1. Field of the Invention
This invention relates to slide fasteners made of synthetic resin having regularly spaced elements formed and fixed to the edges of fastener tapes by the injection molding of a molten mass of the synthetic resin.
2. Description of the Prior Art
Heretofore, in the field of slide fasteners of synthetic resin, the practice of manufacturing slide fasteners pigmented in various colors for the sake of meeting customer's diversified needs has been in vogue.
Generally the injection molding process is utilized for the purpose of promoting the diversification of slide fasteners in color. To be specific, slide fastener chains are manufactured by first dyeing a fabric fastener tape in a desired color, introducing the dyed fastener tape into an injection molding machine, melting resin chips pigmented in a color coordinated with the color of the dyed fastener tape, and injecting the molten resin thereby forming and fixing the elements to the edge of the strip of the fastener tape. Thus, the impartation of one same color to the fastener tape and the elements is effected.
The conventional method described above may deserve to be rated as a means fit for mass production. It is, however, unfit for the recent trend of manufacturing slide fasteners in small lots with diversification in color. This is because each time the color of the fastener tape is changed, the resin chips to be supplied to the injection molding machine must be reformulated to acquire a color conforming to the new color of the fastener tape and the work of changing the color turns out to be a highly complicated and time-consuming operation.
Though an idea of equipping the slide fastener plant with as many injection molding machines as the colors of fastener tape to be preselected for use in the plant is conceivable, this equipment entails huge expense and proves unfit for production of slide fasteners in small lots.